Load handling portable gantry cranes are well known in industry for the lifting and movement of heavy loads from one location to another within a shop or other industrial facility. A typical gantry of this sort is described in Canadian Pat. No. 926,822. To move such gantries from one place to another, or to turn the gantry, swivel casters are provided adjacent the bottom of each supporting leg, and the gantries are either manually pushed or pulled about, or are moved with the aid of a tractor. Such gantries may also be mounted on rails for simple back-and-forth movement, again usually by hand, but also by means of a power driven wheel.
The manual movement of gantries can be difficult particularly when heavy loads are involved, and although this can be alleviated to a certain extent by the use of rails, freedom of movement is then lost. There can also be an element of danger from swinging loads or when trying to control the gantries when being moved.